The present disclosure relates to a reagent holder for an analytical instrument, a reagent supply system for an analytical instrument and an analytical instrument.
Analytical instruments and more particularly medical analytical instruments can serve to examine body fluids, especially blood. Modern instruments of this kind are largely fully automatic in operation, only the samples still having to be inserted in appropriate sample vessels and the desired analysis entered.
The present disclosure is intended for instruments which operate with liquid reagents contained in reagent vessels made of plastic. The instruments usually have a cooled reagent space. The reagents are transported in the instrument from the reagent vessels to the reaction vessels and there mixed with the sample and, after completion of the reaction, a physically detectable change is measured as a measure of the analysis. The measurement may be based on a coloring or an electrochemical detection. The reagent vessels are frequently specially adapted to the reagent space of a particular instrument. By this, space-saving accommodation and effective cooling of the reagents is possible. Reagent vessels and the reagent space of the instrument belonging to them, if they are functionally adapted to each other, form a system called a reagent supply system. Alternatively, the reagent vessel may comprise a system reagent such as a cleaning liquid for cleaning the instrument. Such system reagents are not cooled.
For the transport of the reagents from the reagent vessel into the reaction vessel, essentially two basically different techniques are used, namely the pipetting technique and the dispenser technique.
In the pipetting technique, a pipette, usually fastened to a movable arm, dips from above through the open reagent vessel and an appropriate amount of reagent is sucked in and transferred in the pipette (which is also known as a transfer needle) to the reaction vessel. This technique makes it possible to change the reagent vessels easily. A complicated instrument mechanism is however required. Also the transfer of reagents is relatively slow, as a result of which the throughput rate of the instrument is limited.
With the dispenser technique, the reagent vessels are permanently connected individually by a line to the instrument. The connection lines are a part of a line system through which the reagents are supplied in a suitable manner to the reaction vessels and thereby to the analysis. By this means, with relatively little mechanical complication, they are always available. This allows high analysis frequencies and thereby very rapidly operating automatic, analyzers.
The dispenser technique has however considerable disadvantages with regard to handling. Usually, flexible connecting tubes are introduced from above into the reagent vessels so that they end just above the vessel bottom. This is difficult and can easily lead to errors. In particular, it can occur that air is sucked in if the flexible tubes do not dip deeply enough into the reagent. Also when the flexible tubes are interchanged they must each time be washed in cleaning liquid in order to prevent the transfer of reagent, especially if—as is often customary—various reactions are carried out in the same channel of the instrument and accordingly different reagents are led through one flexible tube.
A known reagent supply system for a medical analytical instrument includes a reagent space provided on the instrument and reagent vessels which are received in the reagent space. In the reagent space, at least one reagent vessel compartment with a bottom, lateral guide elements and a top guiding element as well as a front stop are provided. The instrument contains a fluid communication system for connection with the reagent vessel situated in the reagent vessel compartment. On the end face of the reagent vessel compartment, a hollow needle near the bottom surface thereof is disposed and extends in a direction which is parallel to the bottom surface. On its front wall facing the end face, the reagent vessel has a pierceable seal with a pierceable elastic stopper which is pierced by the hollow needle.
Using such a reagent supply system for a medical analytical instrument provides advantages concerning the handling. Nevertheless, there are still some drawbacks. The process of piercing the reagent vessel requires an accurate operation by the operator as otherwise the hollow needle may be damaged or even broken. Further, the reagent vessels comprise different sizes or widths. Thus, some reagent vessels do not fit into the reagent vessel compartments or need high force to be loaded into the vessel compartment. The reason is that even though the reagent vessels fit within the prescribed reagent vessel tolerances, a variation of the width and the height is unavoidable due to the manufacturing process such as extrusion blow molding. Some reagent vessels comprise bulging even in an empty state which is increased after being filled due to the hydrostatic pressure. Such reagent vessels are squeezed in the reagent vessel compartment. For this reason, the reagent vessel holder comprises tolerances in its dimensions for allowing insertion of such reagent vessel. Another reason for the problems is that narrow bottles have a margin/play in the reagent vessel compartment. The play leads to an off-center piercing of the needle. Thus, the piercing is carried out in the thick wall of the septum provided in the bottle which may cause the needle to be broken.
Therefore, there is a need for a reagent vessel holder for an analytical instrument, a reagent supply system for an analytical instrument and an analytical instrument which are easier and more reliably to be handled and allow compensating tolerances of different reagent vessels without deviating from a center piercing of the needle.